根据句意和首字母填单词：

There are four s　　　　 in a year.

单词填空：根据所给括号中的词填空。

Later, he became ________ in science very much. (interest)

单词填空：根据所给括号中的词填空。

What will be the population of the world by the end of the ________ century?(twenty-one)

单词填空：根据所给括号中的词填空。

I kept on ________ about the match. (think)

单词填空：根据所给括号中的词填空。

She didn't come to school yesterday because of ________. (ill)

单词填空：根据所给括号中的词填空。

Look! How ________ Jim is laughing. (happy)

单词填空：根据所给首字母填空。

We can't leave the students by t　　　　.

单词填空：根据所给首字母填空。

Edison was a great American i　　　　.

单词填空：根据所给首字母填空。

Satellites are used by people for studying the u　　　　.

单词填空：根据所给首字母填空。

Beijing is the c　　　　of China.